1. Field of the Invention
The invention relates to a touch system and a using method thereof, and relates particularly to an optical touch system and a using method thereof.
2. Description of Related Art
Along with rapid developments in industrial technology, touch type electronic products have gradually become the mainstream trend in the market. Out of conventionally used resistive touch screens, capacitive touch screens and rear projection touch screens, the touch effects of a capacitive touch screen are the best, however the cost thereof is also the most expensive and increases along with the increasing size of the screen. Therefore, this limits the use of capacitive touch screens. Searching for an alternative to the capacitive touch screen, currently there is an optical touch screen which uses optical lenses to detect a touch position. The optical touch screen has advantages such as low cost and good accuracy, thus having an advantage in a competitive market and currently has become an alternative option for large sized touch screens.
In regards to a reflective optical touch screen, a plurality of sensing modules including a light source and a light sensing unit are disposed at a periphery of the screen of the reflective optical touch screen, and the touch object has light reflecting material. When the touch object performs a touch input to the screen, the light reflecting material of the touch object reflects a light provided by the light source back to the light sensing unit. Then sensing is performed and from there a position of the touch object is calculated. In this way, in optical touch technology, how to make the light reflected by the touch object fall within a range receivable by the light sensing unit is highly important. However, flattening a surface of a large sized touch screen is not easy, causing the light reflected to the light sensing unit to easily fall outside of the range receivable by the light sensing unit. In order to solve this problem, an area sensor with a larger light receiving range is selected to be adopted for the light sensing unit to replace a typical line sensor. The signal received by an area sensor is a two-dimensional (2D) signal and a 2D sensing image is produced. If analysis is performed on all of the 2D signals during the process of touch sensing, more time is easily consumed. Therefore, a suitable reference line may be first set in the 2D sensing image to perform analysis on the sensing signal according to the light falling on the reference line.
Bearing on the above, to prevent the touch object (such as a stylus) producing an excessive striking sound when performing touch input on the screen, a rubber pad and the like cushioning material used to contact the screen may be disposed on the touch object below the reflective material. However, the smaller the distance between the touch object and the light sensing unit, then the greater the area the cushioning material will take up in the 2D sensing image of the light sensing unit, which makes the reference line in the 2D sensing image to be covered or taken up by the cushioning material, causing the light reflected by the reflective material that arrives at the light sensing unit to be unable to fall on the reference line, thus producing an adverse influence for the touch sensing effects of the optical touch screen.